#include <vector>
using namespace std;
int uniquePaths(int m, int n) {
  vector<vector<int>> dp(m, vector<int>(n, 1));
  for (int i = 1; i < m; ++i) {
    for (int j = 1; j < n; ++j) {
      dp[i][j] = dp[i - 1][j] + dp[i][j - 1];
    }
  }
  return dp[m - 1][n - 1];
}